As a method of forming a thin film such as a silicon oxide film (SiO2) on a substrate such as a semiconductor wafer (hereinafter, referred to as “wafer”), there is known a film formation apparatus which performs ALD (Atomic Layer Deposition). In such a film formation apparatus, a horizontal rotary table is installed inside a processing container (vacuum container) whose interior is kept in a vacuum atmosphere by exhaustion, and the wafer is mounted on the rotary table.
A raw material gas supply part and a reactant gas supply pail are disposed above the rotary table, while being spaced apart from each other in a circumferential direction of the rotary direction. The raw material gas supply part supplies a raw material gas containing a raw material of the thin film, and the reactant gas supply part supplies a reactant gas reacting with the raw material gas adsorbed onto the wafer. The wafer revolves with the rotation of the rotary table so that the wafer repeatedly and alternately passes through a raw material gas supply region to which the raw material gas is supplied and a reactant gas supply region to where the reactant gas is supplied. In this way, the ALD method is performed.
A ceiling portion of the vacuum container may be transformed by a difference in pressure between the outside of the vacuum container which is in an atmospheric environment and the inside of the vacuum container which has been vacuum-exhausted. To prevent this, it is considered that the ceiling portion is supported by a pillar formed to extend from a bottom portion of the vacuum container. There is known a film formation apparatus in which such a pillar is installed. However, in such a film formation apparatus, a worker needs to perform maintenance such as the replacement of a degraded part inside the vacuum container. Even in a case where the pillar is installed, the maintenance is required to be easily performed by the worker. The pillar of the film formation apparatus structured as above seems to be installed integrally to the cover part and the bottom portion of the vacuum container. In addition, the conventional apparatus did not disclose how to open the vacuum container and perform the maintenance. This may not be sufficient to meet the requirement.